The present invention relates to a safety switch.
Safety switches are well known, and are typically used to prevent access to, for example, electromechanical machinery when that machinery is in operation. In a conventional arrangement, the safety switch is mounted on a door post of a machine guard, and an actuator for the safety switch is mounted on a corresponding door. When the door is closed the actuator engages with the safety switch, which in turn closes a set of electrical contacts which allows electricity to be supplied to the machinery. This arrangement ensures that electricity can only be supplied to the machinery when the machine guard door is shut. When the guard door is opened, the actuator disengages from the safety switch, thereby opening the electrical contact and cutting off the supply of electricity to the machinery.
In some instances the set of electrical contacts can become welded together due to the large currents that often flow through the contacts of safety switches. When the contacts weld together, the contacts behave as if they are closed, allowing power to be supplied to the machinery. Even if it is possible to disengage the actuator from the safety switch, the contacts may remain welded together and electricity may still be supplied to the machinery in the machine guard. Thus, if the contacts weld together, power can be supplied to the machinery even when the guard door is open. This can be dangerous, since if the contacts become welded closed, a user can enter the machine guard when the machinery is in operation.
It is an object of the present invention to overcome or substantially mitigate the above mentioned disadvantages.